sim,tests: Add unit test for sim/serialize.hh

Add a unit test for sim/serialize.hh.

==Bugs==
arrayParamIn cannot parse strings with spaces. Since spaces
are used as delimiters, strings containing spaces are parsed
as multiple entries of the array. The test that checks for
this has been disabled.

==Unexpected Behavior==
Serialization has an unexpected behavior when returning to
previous scopes. For example,

  ...
  SCS scs(cpt, "S1")
  paramOut(cpt, "param1", integer1)
  {
    SCS scs_2(cpt, "S2")
    paramOut(cpt, "param2", integer2)
  }
  paramOut(cpt, "param3", integer3)

will generate the output:
  ...
  [S1]
    param1=1
  [S2]
    param2=2
    param3=3

But the user might expect:
  ...
  [S1]
    param1=1
  [S2]
    param2=2
  [S1]
    param3=3

==Incovenient Behavior==
arrayParamIn with a std::array parameter is slightly
incovenient, since the raw data pointer must be extracted.
It may be worth it to add a template specialization.

==Not Tested==
paramInImpl is not being directly tested because it should
not be used as an external API - paramIn and optParamIn
should be used instead.

arrayParamIn with an InsertIterator parameter is not being
directly tested because the other versions should be used
instead.

Change-Id: If0c8f045aa317790d5fcb32e48629b113b62efc5
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/41337
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>

src/base/SConscript

@@ -57,7 +57,7 @@ GTest('coroutine.test', 'coroutine.test.cc', 'fiber.cc')
 Source('framebuffer.cc')
 Source('hostinfo.cc')
 Source('inet.cc')
-Source('inifile.cc')
+Source('inifile.cc', add_tags='gem5 serialize')
 GTest('inifile.test', 'inifile.test.cc', 'inifile.cc', 'str.cc')
 GTest('intmath.test', 'intmath.test.cc')
 Source('logging.cc')
@@ -75,7 +75,7 @@ if env['TARGET_ISA'] != 'null':
 Source('socket.cc')
 GTest('socket.test', 'socket.test.cc', 'socket.cc')
 Source('statistics.cc')
-Source('str.cc', add_tags='gem5 trace')
+Source('str.cc', add_tags=['gem5 trace', 'gem5 serialize'])
 GTest('str.test', 'str.test.cc', 'str.cc')
 Source('time.cc')
 Source('version.cc')

src/base/gtest/serialization_fixture.hh

@@ -0,0 +1,119 @@
+/*
+ * Copyright (c) 2021 Daniel R. Carvalho
+ * All rights reserved
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met: redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer;
+ * redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution;
+ * neither the name of the copyright holders nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <gtest/gtest.h>
+
+#include <cassert>
+#include <cerrno>
+#include <fstream>
+#include <string>
+
+#include "base/compiler.hh"
+#include "sim/serialize.hh"
+
+namespace gem5
+{
+
+/**
+ * Fixture class that handles temporary directory creation. These temporary
+ * directories are used by the tests in this file, in order to avoid that
+ * a failed test will not remove its directory, causing future runs to fail.
+ * This has been tailored for checkpoints, so it expects that the directory
+ * may contain a cpt file on removal.
+ *
+ * @todo Ideally the checkpoints should not be necessarily using files, and
+ *       stringstreams would be used instead to avoid overhead in the tests.
+ */
+class SerializationFixture : public ::testing::Test
+{
+  private:
+    /**
+     * Temporary directory names are generated based on this number, which
+     * is updated every time the generator function is called.
+     */
+    static unsigned dirNumber;
+
+    /** The name of the temporary directory. */
+    std::string dirName;
+
+  public:
+    using ::testing::Test::Test;
+
+    /** Generate a temporary directory name. */
+    static std::string
+    generateTempDirName()
+    {
+        return "/tmp/temp_dir_test" + std::to_string(dirNumber++) + "/";
+    }
+
+    /** Get the name of the directory we have created on SetUp. */
+    std::string getDirName() const { return dirName; }
+
+    /** Get the path to the checkpoint file. */
+    std::string
+    getCptPath() const
+    {
+        return getDirName() + std::string(CheckpointIn::baseFilename);
+    }
+
+    /**
+     * Create a cpt file with the contents specified by the string. This
+     * function should be used when testing unserialization, since it
+     * simulates a previous serialization.
+     */
+    void
+    simulateSerialization(std::string contents) const
+    {
+        std::ofstream cp(getCptPath());
+        cp << contents;
+        cp.close();
+    }
+
+    void
+    SetUp() override
+    {
+        // Create the directory
+        dirName = generateTempDirName();
+        M5_VAR_USED int success = mkdir(dirName.c_str(), 0775);
+        assert(!(success == -1 && errno != EEXIST));
+    }
+
+    void
+    TearDown() override
+    {
+        // There may be a cpt file inside, so try to remove it; otherwise,
+        // rmdir does not work
+        std::remove(getCptPath().c_str());
+        // Remove the directory we created on SetUp
+        M5_VAR_USED int success = rmdir(dirName.c_str());
+        assert(success == 0);
+    }
+};
+unsigned SerializationFixture::dirNumber = 0;
+
+} // anonymous namespace

src/sim/SConscript

@@ -63,7 +63,7 @@ Source('port.cc')
 Source('python.cc', add_tags='python')
 Source('redirect_path.cc')
 Source('root.cc')
-Source('serialize.cc')
+Source('serialize.cc', add_tags='gem5 serialize')
 Source('drain.cc')
 Source('se_workload.cc')
 Source('sim_events.cc')
@@ -87,10 +87,13 @@ Source('stats.cc')
 Source('workload.cc')
 Source('mem_pool.cc')
 
+env.TagImplies('gem5 serialize', 'gem5 trace')
+
 GTest('byteswap.test', 'byteswap.test.cc', '../base/types.cc')
 GTest('guest_abi.test', 'guest_abi.test.cc')
 GTest('port.test', 'port.test.cc', 'port.cc')
 GTest('proxy_ptr.test', 'proxy_ptr.test.cc')
+GTest('serialize.test', 'serialize.test.cc', with_tag('gem5 serialize'))
 GTest('serialize_handlers.test', 'serialize_handlers.test.cc')
 
 if env['TARGET_ISA'] != 'null':